The instant invention relates to washing apparatus and in particular to dispensers for dispensing a preselected quantity of detergent and rinse aid additives at preselected times into washing liquid during a washing and a rinsing operation.
Conventional dishwashers effect cleaning by means of a preselected timed sequence of wash and rinse cycles in which different additives are introduced into the dishwashing chamber. Thus, detergent may be dispensed at different times during the wash cycle and rinse additives to provide improved rinsing of the washed dishes may be dispensed during the final rinse cycle. Automatic dispensers which operate in preselected timed sequence have been provided in the past to affect these dispensing operations. For example, a common rinse aid injector in use today includes a relatively expensive solenoid to operate the metering or dispensing mechanism. Since the solenoid is used, there is also an additional switch required in the sequence control means. Moreover, the solenoid operated device does not provide selectivity of operation without the employment of a second additional switch to override the switch in the sequence control means. Selectivity, as used herein, means the ability to operate a diswasher through a full cycle with, or without, rinse aid being injected at the selection of the user. With a solenoid operated dispenser, it is necessary to position an additional selection switch in electrical series with a solenoid to override the sequence control means switch in the event it is desired to omit the dispensing during a particular wash cycle. Devices have been shown such as in U.S. Pat. No.3,198,387 whereby the operator of an automatic washing machine may select a cycle during which the dispensing means will operate by manipulating a manually operable means. This particular device, however, relates solely to a rinse aid injector independent of the detergent dispensing mechanism and therefore requires the operator to remember when to activate or not activate the rinse aid dispenser depending on which operational cycle is selected.
With most prior art devices the rinse aid dispenser was normally activated whenever the operator put the machnine in a rinse and hold cycle. This of course would release the rinse aid unnecessarily and adversely affect the rinsing operation and the later washing operation. Prior art devices are known which are relatively complex apparatus for preventing activation of the rinse aid dispenser. See for example the bimetal element and its related structure shown in commonly assigned U.S. Pat. No.3,212,675.
It would be most advantageous to provide economical dispensing structure for both detergent and rinse aid additive which would be operably interconnected such that the system would automatically prevent the operation of the rinse injector whenever the detergent is not used, such as in, what is commonly referred to as, the "rinse and hold" cycle.